Beta-thalassemia, also nown as Cooley's Anemia, is an hereditary disease characterized by severe anemia. The anemia is a consequence of a low level of beta chains of hemoglobin being produced by the patient's red blood cells. This results in an excess of alpha globin chains. These excess alpha chains precipitate in the cell and lead to the destruction of the cell. No amino acid change has been found in the hemoglobin beta chains of thalassemic patients. It is generally assumed, therefore, that the molecular abnormality from thalassemia cells has indicated that there is a reduced amount of beta globin mRNA relative to that for the alpha globin, so that the defect must be specifically in the production of messenger RNA. The normal mechanisms for regulation of globin mRNA production and the nature of the defect in beta thalassemia cells are being investigated. The relative amount of alpha and beta globin messenger RNA sequences synthesized from thalassemic and non-thalassemic chromatin in the cell-free RNA synthesizing system will be quantitated. Fractionation of the nuclear components of thalassemic erythroid cells will be carried out to determine the molecular defect in thalassemia.